The utilization of x-rays and other photographic medium for obtaining data relative to the structural characteristics of an object has been known for many years. Images are often encountered wherein the features of interest may be separated from their surroundings by only a small difference in brightness, thus making the examination or even the detection of these features a difficult proposition for a human inspecting the same. The images of interest may be in an electronic form such as the video information being fed to a closed circuit television monitor, or in photographic form such as in x-ray or nuclear radiograph of a part being inspected for cracks and other flaws. Of course, medical radiographs and the interpretation thereof are also subject to such problems. An additional difficulty in the case of radiographs stems from the somewhat limited ability of the human eye to observe minute density differences in those portions of the photographic transparencies with near zero density (almost transparent) and in portions with high density (almost no light transmittance).
In order to make maximum use of the photographic images discussed hereinabove, a device and technique must be implemented for enhancing the contrast of an image at all levels of density (or brightness) without exceeding the dynamic range of the display medium (cathode ray tube monitor, or film) and without exceeding the dynamic range of the human utilizing the same.
Consequently, it is an object of the instant invention to present a method and apparatus for enhancing data whereby data recorded on a first media in accordance with a first transfer function may again be recorded on a second medium in accordance with a second transfer function, the second transfer function being an enhancement of the first.
Yet another object of the invention is to present a method and apparatus for enhancing data whereby imaged data may be digitized, the digitized values shifted, and re-imaged so as to present an enhanced image structure.
Still another object of the invention is to present a method and apparatus for enhancing data whereby image data may be digitized, and the digitized data be shifted and offset an incremental amount so as to provide for maximum enhancement between background structure and subtle features.
Still another object of the invention is to present a method and apparatus for enhancing data whereby the positioning and size of a flaw within an object may be determined.
Still a further object of the invention is to present a method and apparatus for enhancing data which is inexpensive, reliable, and easily developed from the state of the art.
These objects and other objects which will become apparent as the detailed description proceeds are achieved by a technique and apparatus for initially digitizing the density-related signal achieved from scanning an object film, offsetting that digitized value, shifting the values towards the most significant bit to achieve the desired enhancement, and reconverting the signals to an analog signal, if need be, for reproduction in a common film recorder of an enhanced film.